In instances in radiant energy examination of objects, need exists for providing a sequence of records, for example, developed photographic film strips, indicating radiant energy reflected by an object in the course of permutations in projected radiant energy. The record sequence is then examined by examining successive film frames to determine, by the contents thereof, the effect of the radiant energy projection permutations. By way of example of this practice, in U.S. Pat. No. 3,866,052, involving applicant herein, a practice is disclosed wherein an object surface is irradiated successively through different radiant energy transmissive masks and records are made of the object surface return for each such irradiation. In accordance with the spatial location of the object surface in relation to the lens of the recording apparatus, and further depending upon the structure of the masks, the object surface will be evidenced only in selective of the records. For purposes of providing indication of the object surface spatial location, signals are generated from examination of the records, with the signals being indicative both of the number of records in the succession and those particular records evidencing a return from the object surface.
This practice of the U.S. Pat. No. 3,866,052 is somewhat encumbered by its need for film frames in number equal to the number of individual radiant energy projections. Thus, if the number of different masks employed in the projection sequence is 10, 10 film frames are employed. The cost of such practice is accordingly increased by film consumption and the time involved in separately examining each film frame.